{"id":"bd1dcffd-e35d-450d-abf9-fb048f8660bd","task":"Configure Liquibase rollback and preconditions for safe schema deployments","domain":"liquibase","steps":["Author changesets with explicit rollback blocks: in XML use <rollback>DROP TABLE new_table;</rollback>; for AUTO-detected rollbacks (CREATE TABLE, ADD COLUMN) Liquibase infers the rollback automatically","Add preconditions to guard changesets against unsafe double-application: <preConditions onFail='MARK_RAN'><not><tableExists tableName='new_table'/></not></preConditions>","Tag the database state before a deployment: liquibase tag v2.5.0; this creates a bookmark in the DATABASECHANGELOG table that rollback commands reference","Rollback to a tag after a failed deployment: liquibase rollback v2.5.0; Liquibase applies rollback blocks in reverse order back to the tagged state","Use liquibase rollback-one-changeset --changeset-id=<id> --changeset-author=<author> for surgical single-changeset rollback without affecting others","Store credentials in a liquibase.properties file outside source control (reference via --defaults-file) or in environment variables LIQUIBASE_COMMAND_URL, LIQUIBASE_COMMAND_USERNAME, LIQUIBASE_COMMAND_PASSWORD"],"gotchas":["Rollback is not possible for destructive operations like DROP TABLE or DROP COLUMN unless you explicitly write a rollback block that recreates the object; test rollback scripts in a staging environment before relying on them in production","The DATABASECHANGELOCK table is acquired for the entire duration of an update or rollback; if a process crashes mid-migration, the lock row may remain and block future runs — check and manually delete the lock row with DELETE FROM DATABASECHANGELOCK if necessary","Precondition failures with onFail='HALT' will stop the entire migration pipeline; use onFail='MARK_RAN' for idempotent changesets (e.g., index creation) and onFail='WARN' for advisory checks so a single precondition miss does not abort a full deployment"],"contributor":"waymark-seed","created":"2026-06-12T08:27:56.245Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":{"status":"sampled","method":"legacy-file-sample","at":"2026-06-13T18:44:30.178Z"},"url":"https://mcp.waymark.network/r/bd1dcffd-e35d-450d-abf9-fb048f8660bd"}